The present invention relates to a fish sonar buoy for detecting a school of fish in a desired deep portion in the sea.
Generally, a fish sonar is well known in which an ultrasonic transducer is provided with the bottom or side of a fishing boat. In the fish sonar, the ultrasonic signal is emitted from the ultrasonic transducer, the ultrasonic echo signals being reflected from schools of fish, the bottom and so on in the sea, are received again and transformed into electric signals by the ultrasonic transducer. The electric signals are processed by a receiving circuit and are displayed on a cathode ray tube or recorded by a recorder.
A condition near or below the fishing boat is detected by the prior fish sonar, but a condition in the sea apart from the fishing boat cannot be detected. Therefore, when the angler fishes by mooring a boat, he must move the fishing boat for detecting a condition in the sea apart from the fishing boat. Also, the same occurs when an angler fishes with a fishing rod in a quay, a condition in the sea where a fish-hook is cast is not detected by a prior fish sonar.